1 #ifndef _I386_BITOPS_H 2 #define _I386_BITOPS_H 3 4 /* 5 * Copyright 1992, Linus Torvalds. 6 */ 7 8 9 /* 10 * These have to be done with inline assembly: that way the bit-setting 11 * is guaranteed to be atomic. All bit operations return 0 if the bit 12 * was cleared before the operation and != 0 if it was not. 13 * 14 * bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1). 15 */ 16 17 #include <asm-generic/bitops/fls.h> 18 #include <asm-generic/bitops/__fls.h> 19 #include <asm-generic/bitops/fls64.h> 20 21 #ifdef CONFIG_SMP 22 #define LOCK_PREFIX "lock ; " 23 #else 24 #define LOCK_PREFIX "" 25 #endif 26 27 #define ADDR (*(volatile long *) addr) 28 29 /** 30 * set_bit - Atomically set a bit in memory 31 * @nr: the bit to set 32 * @addr: the address to start counting from 33 * 34 * This function is atomic and may not be reordered. See __set_bit() 35 * if you do not require the atomic guarantees. 36 * Note that @nr may be almost arbitrarily large; this function is not 37 * restricted to acting on a single-word quantity. 38 */ 39 static __inline__ void set_bit(int nr, volatile void * addr) 40 { 41 __asm__ __volatile__( LOCK_PREFIX 42 "btsl %1,%0" 43 :"=m" (ADDR) 44 :"Ir" (nr)); 45 } 46 47 /** 48 * __set_bit - Set a bit in memory 49 * @nr: the bit to set 50 * @addr: the address to start counting from 51 * 52 * Unlike set_bit(), this function is non-atomic and may be reordered. 53 * If it's called on the same region of memory simultaneously, the effect 54 * may be that only one operation succeeds. 55 */ 56 static __inline__ void __set_bit(int nr, volatile void * addr) 57 { 58 __asm__( 59 "btsl %1,%0" 60 :"=m" (ADDR) 61 :"Ir" (nr)); 62 } 63 64 #define PLATFORM__SET_BIT 65 66 /** 67 * clear_bit - Clears a bit in memory 68 * @nr: Bit to clear 69 * @addr: Address to start counting from 70 * 71 * clear_bit() is atomic and may not be reordered. However, it does 72 * not contain a memory barrier, so if it is used for locking purposes, 73 * you should call smp_mb__before_clear_bit() and/or smp_mb__after_clear_bit() 74 * in order to ensure changes are visible on other processors. 75 */ 76 static __inline__ void clear_bit(int nr, volatile void * addr) 77 { 78 __asm__ __volatile__( LOCK_PREFIX 79 "btrl %1,%0" 80 :"=m" (ADDR) 81 :"Ir" (nr)); 82 } 83 #define smp_mb__before_clear_bit() barrier() 84 #define smp_mb__after_clear_bit() barrier() 85 86 /** 87 * __change_bit - Toggle a bit in memory 88 * @nr: the bit to set 89 * @addr: the address to start counting from 90 * 91 * Unlike change_bit(), this function is non-atomic and may be reordered. 92 * If it's called on the same region of memory simultaneously, the effect 93 * may be that only one operation succeeds. 94 */ 95 static __inline__ void __change_bit(int nr, volatile void * addr) 96 { 97 __asm__ __volatile__( 98 "btcl %1,%0" 99 :"=m" (ADDR) 100 :"Ir" (nr)); 101 } 102 103 /** 104 * change_bit - Toggle a bit in memory 105 * @nr: Bit to clear 106 * @addr: Address to start counting from 107 * 108 * change_bit() is atomic and may not be reordered. 109 * Note that @nr may be almost arbitrarily large; this function is not 110 * restricted to acting on a single-word quantity. 111 */ 112 static __inline__ void change_bit(int nr, volatile void * addr) 113 { 114 __asm__ __volatile__( LOCK_PREFIX 115 "btcl %1,%0" 116 :"=m" (ADDR) 117 :"Ir" (nr)); 118 } 119 120 /** 121 * test_and_set_bit - Set a bit and return its old value 122 * @nr: Bit to set 123 * @addr: Address to count from 124 * 125 * This operation is atomic and cannot be reordered. 126 * It also implies a memory barrier. 127 */ 128 static __inline__ int test_and_set_bit(int nr, volatile void * addr) 129 { 130 int oldbit; 131 132 __asm__ __volatile__( LOCK_PREFIX 133 "btsl %2,%1\n\tsbbl %0,%0" 134 :"=r" (oldbit),"=m" (ADDR) 135 :"Ir" (nr) : "memory"); 136 return oldbit; 137 } 138 139 /** 140 * __test_and_set_bit - Set a bit and return its old value 141 * @nr: Bit to set 142 * @addr: Address to count from 143 * 144 * This operation is non-atomic and can be reordered. 145 * If two examples of this operation race, one can appear to succeed 146 * but actually fail. You must protect multiple accesses with a lock. 147 */ 148 static __inline__ int __test_and_set_bit(int nr, volatile void * addr) 149 { 150 int oldbit; 151 152 __asm__( 153 "btsl %2,%1\n\tsbbl %0,%0" 154 :"=r" (oldbit),"=m" (ADDR) 155 :"Ir" (nr)); 156 return oldbit; 157 } 158 159 /** 160 * test_and_clear_bit - Clear a bit and return its old value 161 * @nr: Bit to set 162 * @addr: Address to count from 163 * 164 * This operation is atomic and cannot be reordered. 165 * It also implies a memory barrier. 166 */ 167 static __inline__ int test_and_clear_bit(int nr, volatile void * addr) 168 { 169 int oldbit; 170 171 __asm__ __volatile__( LOCK_PREFIX 172 "btrl %2,%1\n\tsbbl %0,%0" 173 :"=r" (oldbit),"=m" (ADDR) 174 :"Ir" (nr) : "memory"); 175 return oldbit; 176 } 177 178 /** 179 * __test_and_clear_bit - Clear a bit and return its old value 180 * @nr: Bit to set 181 * @addr: Address to count from 182 * 183 * This operation is non-atomic and can be reordered. 184 * If two examples of this operation race, one can appear to succeed 185 * but actually fail. You must protect multiple accesses with a lock. 186 */ 187 static __inline__ int __test_and_clear_bit(int nr, volatile void * addr) 188 { 189 int oldbit; 190 191 __asm__( 192 "btrl %2,%1\n\tsbbl %0,%0" 193 :"=r" (oldbit),"=m" (ADDR) 194 :"Ir" (nr)); 195 return oldbit; 196 } 197 198 /* WARNING: non atomic and it can be reordered! */ 199 static __inline__ int __test_and_change_bit(int nr, volatile void * addr) 200 { 201 int oldbit; 202 203 __asm__ __volatile__( 204 "btcl %2,%1\n\tsbbl %0,%0" 205 :"=r" (oldbit),"=m" (ADDR) 206 :"Ir" (nr) : "memory"); 207 return oldbit; 208 } 209 210 /** 211 * test_and_change_bit - Change a bit and return its new value 212 * @nr: Bit to set 213 * @addr: Address to count from 214 * 215 * This operation is atomic and cannot be reordered. 216 * It also implies a memory barrier. 217 */ 218 static __inline__ int test_and_change_bit(int nr, volatile void * addr) 219 { 220 int oldbit; 221 222 __asm__ __volatile__( LOCK_PREFIX 223 "btcl %2,%1\n\tsbbl %0,%0" 224 :"=r" (oldbit),"=m" (ADDR) 225 :"Ir" (nr) : "memory"); 226 return oldbit; 227 } 228 229 #if 0 /* Fool kernel-doc since it doesn't do macros yet */ 230 /** 231 * test_bit - Determine whether a bit is set 232 * @nr: bit number to test 233 * @addr: Address to start counting from 234 */ 235 static int test_bit(int nr, const volatile void * addr); 236 #endif 237 238 static __inline__ int constant_test_bit(int nr, const volatile void * addr) 239 { 240 return ((1UL << (nr & 31)) & (((const volatile unsigned int *) addr)[nr >> 5])) != 0; 241 } 242 243 static __inline__ int variable_test_bit(int nr, volatile void * addr) 244 { 245 int oldbit; 246 247 __asm__ __volatile__( 248 "btl %2,%1\n\tsbbl %0,%0" 249 :"=r" (oldbit) 250 :"m" (ADDR),"Ir" (nr)); 251 return oldbit; 252 } 253 254 #define test_bit(nr,addr) \ 255 (__builtin_constant_p(nr) ? \ 256 constant_test_bit((nr),(addr)) : \ 257 variable_test_bit((nr),(addr))) 258 259 /** 260 * find_first_zero_bit - find the first zero bit in a memory region 261 * @addr: The address to start the search at 262 * @size: The maximum size to search 263 * 264 * Returns the bit-number of the first zero bit, not the number of the byte 265 * containing a bit. 266 */ 267 static __inline__ int find_first_zero_bit(void * addr, unsigned size) 268 { 269 int d0, d1, d2; 270 int res; 271 272 if (!size) 273 return 0; 274 /* This looks at memory. Mark it volatile to tell gcc not to move it around */ 275 __asm__ __volatile__( 276 "movl $-1,%%eax\n\t" 277 "xorl %%edx,%%edx\n\t" 278 "repe; scasl\n\t" 279 "je 1f\n\t" 280 "xorl -4(%%edi),%%eax\n\t" 281 "subl $4,%%edi\n\t" 282 "bsfl %%eax,%%edx\n" 283 "1:\tsubl %%ebx,%%edi\n\t" 284 "shll $3,%%edi\n\t" 285 "addl %%edi,%%edx" 286 :"=d" (res), "=&c" (d0), "=&D" (d1), "=&a" (d2) 287 :"1" ((size + 31) >> 5), "2" (addr), "b" (addr)); 288 return res; 289 } 290 291 /** 292 * find_next_zero_bit - find the first zero bit in a memory region 293 * @addr: The address to base the search on 294 * @offset: The bitnumber to start searching at 295 * @size: The maximum size to search 296 */ 297 static __inline__ int find_next_zero_bit (void * addr, int size, int offset) 298 { 299 unsigned long * p = ((unsigned long *) addr) + (offset >> 5); 300 int set = 0, bit = offset & 31, res; 301 302 if (bit) { 303 /* 304 * Look for zero in first byte 305 */ 306 __asm__("bsfl %1,%0\n\t" 307 "jne 1f\n\t" 308 "movl $32, %0\n" 309 "1:" 310 : "=r" (set) 311 : "r" (~(*p >> bit))); 312 if (set < (32 - bit)) 313 return set + offset; 314 set = 32 - bit; 315 p++; 316 } 317 /* 318 * No zero yet, search remaining full bytes for a zero 319 */ 320 res = find_first_zero_bit (p, size - 32 * (p - (unsigned long *) addr)); 321 return (offset + set + res); 322 } 323 324 /** 325 * ffz - find first zero in word. 326 * @word: The word to search 327 * 328 * Undefined if no zero exists, so code should check against ~0UL first. 329 */ 330 static __inline__ unsigned long ffz(unsigned long word) 331 { 332 __asm__("bsfl %1,%0" 333 :"=r" (word) 334 :"r" (~word)); 335 return word; 336 } 337 338 #ifdef __KERNEL__ 339 340 /** 341 * __ffs - find first set bit in word 342 * @word: The word to search 343 * 344 * Undefined if no bit exists, so code should check against 0 first. 345 */ 346 static inline unsigned long __ffs(unsigned long word) 347 { 348 __asm__("rep; bsf %1,%0" 349 : "=r" (word) 350 : "rm" (word)); 351 return word; 352 } 353 354 /** 355 * ffs - find first bit set 356 * @x: the word to search 357 * 358 * This is defined the same way as 359 * the libc and compiler builtin ffs routines, therefore 360 * differs in spirit from the above ffz (man ffs). 361 */ 362 static __inline__ int ffs(int x) 363 { 364 int r; 365 366 __asm__("bsfl %1,%0\n\t" 367 "jnz 1f\n\t" 368 "movl $-1,%0\n" 369 "1:" : "=r" (r) : "rm" (x)); 370 371 return r+1; 372 } 373 #define PLATFORM_FFS 374 375 static inline int __ilog2(unsigned int x) 376 { 377 return generic_fls(x) - 1; 378 } 379 380 /** 381 * hweightN - returns the hamming weight of a N-bit word 382 * @x: the word to weigh 383 * 384 * The Hamming Weight of a number is the total number of bits set in it. 385 */ 386 387 #define hweight32(x) generic_hweight32(x) 388 #define hweight16(x) generic_hweight16(x) 389 #define hweight8(x) generic_hweight8(x) 390 391 #endif /* __KERNEL__ */ 392 393 #ifdef __KERNEL__ 394 395 #define ext2_set_bit __test_and_set_bit 396 #define ext2_clear_bit __test_and_clear_bit 397 #define ext2_test_bit test_bit 398 #define ext2_find_first_zero_bit find_first_zero_bit 399 #define ext2_find_next_zero_bit find_next_zero_bit 400 401 /* Bitmap functions for the minix filesystem. */ 402 #define minix_test_and_set_bit(nr,addr) __test_and_set_bit(nr,addr) 403 #define minix_set_bit(nr,addr) __set_bit(nr,addr) 404 #define minix_test_and_clear_bit(nr,addr) __test_and_clear_bit(nr,addr) 405 #define minix_test_bit(nr,addr) test_bit(nr,addr) 406 #define minix_find_first_zero_bit(addr,size) find_first_zero_bit(addr,size) 407 408 #endif /* __KERNEL__ */ 409 410 #endif /* _I386_BITOPS_H */ 411